1. Field of the Invention
This invention relates to the installation of a structure floating on a body of water. More particularly, the invention relates to a floating structure from which drilling or production operations are carried out. It relates especially to the installation of vertically moored platforms (VMP) in deep water.
In recent years there has been considerable attention atracted to the drilling and production of wells located in water. Wells may be drilled in the ocean floor from either fixed platforms in relatively shallow water or from floating structures or vessels in deeper water. The most common means of anchoring fixed platforms includes the driving or otherwise anchoring of long piles in the ocean floor. Such piles extend above the surface of the water and support a platform attached to the top of the pile. This works fairly well in shallow water; but, as the water gets deeper, the problems of design and accompanying costs become prohibitive. In deeper water, it is common practice to drill from a floating structure.
In recent years, attention has been directed toward many different kinds of floating structures. One system receiving attention is the vertically moored platform. Such a platform is described in U.S. Pat. No. 3,648,638, issued Mar. 14, 1972, Kenneth A. Blenkarn, inventor. Key features of the disclosure in that patent are that the floating platform is connected to an anchor on the ocean floor only by elongated parallel members and the floating structure has buoyant means designed especially with respect to the trough of a design wave so as to minimize mooring forces imposed on the vertically elongated members which anchor the structure, such as those forces which may be caused by passing waves.
The closest or most pertinent prior art of which I am aware is the aforesaid U.S. Pat. No. 3,648,638. However, the installation described here is for a different method from the installation method and system described in that patent.